The gray treefrog is a small (1.5-2") arboreal frog. Color is highly variable as they can change color from gray to green depending upon the color of their surroundings.
Eastern broadleaf forests.
I have sometimes found these endearing little frogs near lights at night, where they feed on moths and other insects that attracted to the light. A very similar species, Copes gray treefrog, is indistinguishable from the gray treefrog in the field and their ranges overlap in Minnesota.